Chemistry of zirconia and its use in chromatography

Monodisperse nonaggregated nanoparticles of titania are obtained through hydrolysis at 60 °C of titanium butoxide in the presence of acetylacetone and para-toluenesulfonic acid. After the particles are dried, the resulting xerosols can be dispersed without aggregation in water−alcoholic or alcoholic solutions at concentrations higher than 1 M. The characterizations of the nanoparticles were carried out in solution by using quasi-elastic light scattering (QELS); FTIR; 13C, 17O, and 1H NMR and in solid state by X-ray diffraction, transmission electron microscopy (TEM), FTIR, thermogravimetry−dynamic thermal analysis (TG−DTA), 13C cross-polarization−magic angle spinning (CP−MAS) NMR. The mean size of the anatase oxide core can be adjusted in the 1−5 nm range by a careful tuning of the synthetic conditions. The protection of these particles toward aggregation is ensured through the complexation of the surface by acetylacetonato ligands and through an adsorbed hybrid organic−inorganic layer made with acetylace...

Synthesis and Characterization of Surface-Protected Nanocrystalline Titania Particles

Oxygen is a key chemical element and solid state NMR can provide unique insight into the its local environment. In the last decade there have been significant advances (sensitivity, resolution) in the NMR methodology for non-integer spin quadrupole nuclei such as oxygen and the background to these techniques is presented in this tutorial review. The information that the NMR parameters can provide about the local environment is explained through a series of illustrations from different areas of solid state chemistry and structural science of inorganic materials.

Solid state 17O NMR—an introduction to the background principles and applications to inorganic materials

We show that natural abundance oxygen-17 NMR of solids could be obtained in minutes at a moderate magnetic field strength by using dynamic nuclear polarization (DNP). Electron spin polarization could be transferred either directly to (17)O spins or indirectly via (1)H spins in inorganic oxides and hydroxides using an oxygen-free solution containing a biradical polarization agent (bTbK). The results open up a powerful method for rapidly acquiring high signal-to-noise ratio solid-state NMR spectra of (17)O nuclear spins and to probe sites on or near the surface, without the need for isotope labeling.

Dynamic Nuclear Polarization Enhanced Natural Abundance 17O Spectroscopy

Fluoroaluminate molten salts are used in the Hall-Heroult industrial process for the production of aluminum by electrolysis. To better understand the mechanism of the dissolution of alumina (Al2O3) in cryolitic melts, we have studied the structure of these liquids up to 1025 °C by in-situ NMR of 27Al, 23Na, 19F, and 17O, using a laser-heated experimental setup. From these experiments we can propose a quantification of the different aluminum-bearing species AlF4-, AlF52-, and AlF63- in the liquid and give a direct experimental evidence of the existence of at least two different oxy-fluoride species, Al2OF62- and Al2O2F42-, when dissolving alumina in the fluoride liquid. The obtained results are compared with other spectroscopic data obtained by in-situ Raman spectroscopy.

Structure of High-Temperature NaF−AlF3−Al2O3 Melts: A Multinuclear NMR Study

The following binary metal oxides have yielded high-resolution 17O nuclear magnetic resonance (NMR) spectra, obtained by magic-angle spinning (MAS) without isotopic enrichment: α-Al2O3, TiO2 (anatase and rutile), Ti2O3, monoclinic VO2, Cu2O, ZnO, tetragonal and monoclinic ZrO2, Ag2O, tetragonal SnO, hexagonal La2O3, CeO2, HfO2, α-PbO; also Na β-Al2O3 and cubic MgO-ZrO2. Detection sensitivity limits observation to cases where the nuclear quadrupole coupling is less than 4 MHz. Different ceramic phases can readily be distinguished by their chemical shift. As empirical chemical shift correlation is suggested between 17O in the oxide M2Om, and 19F in the corresponding fluoride MFm.

T. J. Bastow

Papers

17O NMR in simple oxides

17O NMR in Simple Oxides